Butterfly Proboscis to Sip Cells

November 2009— A butterfly's proboscis
looks like a straw -- long, slender, and used for sipping -- but it
works more like a paper towel, according to Konstantin Kornev of
Clemson University. He hopes to borrow the tricks of this piece of
insect anatomy to make small probes that can sample the fluid inside of
cells.

Kornev will present his work at the 62nd Annual Meeting of the
American Physical Society's (APS) Division of Fluid Dynamics will take
place from November 22-24 at the Minneapolis Convention Center.

At the scales at which a butterfly or moth lives, liquid is so thick
that it is able to form fibers. The insects' liquid food -- drops of
water, animal tears, and the juice inside decomposed fruit -- spans
nearly three orders of magnitude in viscosity. Pumping liquid through
its feeding tube would require an enormous amount of pressure.

"No pump would support that kind of pressure," says Kornev. "The liquid would boil spontaneously."

Instead of pumping, Kornev's findings suggest that butterflies draw
liquid upwards using capillary action -- the same force that pulls
liquid across a paper towel. The proboscis resembles a rolled-up paper
towel, with tiny grooves that pull the liquid upwards along the edges,
carrying along the bead of liquid in the middle of the tube. This
process is not nearly as affected by viscosity as pumping.

Kornev has been recently awarded an NSF grant to develop artificial
probes made of nanofibers that use a similar principal to draw out the
viscous liquid inside of cells and examine their contents.

The presentation, "Butterfly proboscis as a biomicrofluidic system"
by Konstantin Kornev et al of Clemson University, is on November 22,
2009.